Machinist vise with independent hydraulic-cylinder structure

ABSTRACT

A machinist vise or other clamping device has a support carrying a stationary jaw, and an axially displaceable clamping body carrying a displaceable jaw mounted on the support. A cylinder having a fluid chamber is structurally independent of the clamping body and mounted therein with an axial projection or boss received in an axial hole or bore in the clamping body. The cylinder has a pair of pistons, one of which is annular and surrounds the other, that are coaxial with the projection and the hole. An actuator is connectable to the larger, annular piston to close the jaws on a workpiece after which it is automatically connected to the inner, smaller piston to apply clamping pressure at an increased mechanical advantage. The axial bore is accessible on removal of the displaceable vise jaw or a liner therefor and is provided with a filling opening for the fluid chamber of the cylinder, a screw normally closing this filling opening and forming a plug therefor. A pressure indicator visible through a port in the clamping body indicates the clamping pressure.

United States Patent Rohm [ MACHINIST VISE WITH INDEPENDENT HYDRAULIC-CYLINDER STRUCTURE [76] Inventor: Giinter Horst Riihm, Muhlstrasse 9,

Sontheim/Brenz, Germany [22] Filed: Oct. 18, 1971 [211 App]. No.: 190,035

[30] Foreign Application Priority Data Oct. 23, 1970 Germany G 70 39 267.5

[52] US. Cl 269/23, 269/24, 269/27 [51] Int. Cl... ..-B25b 1/02, B25b 1/24 [58] Field of Search 269/20, 27, 32, 25, 269/24, 69, 63, 208, 211, 23, 22, 307

[561' References Cited UNITED STATES PATENTS 2,509,991 5/1950 Schenke 269/32 2,803,157 8/1957 Seitter 269/32 X 3,348,836 10/1967 Smierciak.. 269/25 3,484,094 12/1969 Arnold 269/24 FOREIGN PATENTS OR APPLICATIONS 563,735 8/1944 Great Britain 269/23 S594 10/1955 Germany 894,948 10/1953 Germany ..269/32 Nov. 6, 1973 [57] ABSTRACT A machinist vise or other clamping device has a support carrying a stationary jaw, and an axially displaceable clamping body carrying a displaceable jaw mounted on the support. A cylinder having a fluid chamber is structurally independent of the clamping body and mounted therein with an axial projection or boss received in an axial hole or bore in the clamping body. The cylinder has a pair of pistons, one of which is annular and surrounds the other, that are coaxial with the projection and the hole. An actuator is connectable to the larger, annular piston to close the jaws .on a workpiece after which it is automatically connected to the inner, smaller piston to apply clamping pressure at an increased mechanical advantage. The axial bore is accessible on removal of the displaceable vise jaw or a liner therefor and is provided with a filling opening for the fluid chamber of the cylinder, a screw normally closing this filling opening and forming a plug therefor. A pressure indicator visible through a port in the clamping body indicates the clamping pressure.

- 7 Claims, 3 Drawing Figures PATENTEU NOV 6 1975 INVENTOR GUnfer H. Rohm g O0 Attorney MACHINIST VISE WITH INDEPENDENT HYDRAULIC-CYLINDER STRUCTURE FIELD OF THE INVENTION The present invention relates to a clamping device such as a vise. More particularly this invention relates to a machinist vise having two modes of operation fast advance with a low mechanical advantage and slow advance with a high mechanical advantage and a hydraulic link, or force-transmitting member, in the form of a fluid'cylinder with a pair of pistons effecting these modesof operation.

BACKGROUND OF THE INVENTION A machinist vise must be opened and closed frequently for repositioning or changing of the workpiece. At the same time it must be able to grip the workpiece, usually a metal casting or other similarly rigid body, very tightly for such operations as shaping or drilling.

To this end vises have been developed which open and a close rapidly, with of course a very low mechanical advantage, but which automatically switch over to a slowadvance high-mechanical-advantage mode of operation once the jaws engagethe workpiece.

In one form of realization of such a vise, disclosed in my concurrently filed patent application Ser. No. 189,871, there is provided a fluid cylinder having a pair of pistons. One of the pistons is annular and surrounds the other, the central piston having an effective surface area which is much smaller than that of the one surrounding it. A slip clutch is provided to displace both pistons in the cylinder chamber until the displaceable vise jaw meets resistance, whereupon only the central piston is displaced to make theactuator effective with a greatly increased mechanical advantage.

Vises provided with integral or one-piece jaws and fluid cylinders have proven extremely difficult to make. Their fabrication involves the complicated machining of the cylinder directly in the massive steel slide of the Another problem with vises so made lies in the difficulty of filling or refilling of the fluid chamber. This operation often requires disassembling of a major portion of the vise.

SUMMARY OF THE INVENTION This cylinder has an axial projection or boss which is A further disadvantage of such a vise is that it is virtu- OBJECTS OF THE INVENTION It is, therefore, an object of the invention toprovide an improved clamping device, e.g'. a vise of the abovedescribed type.

Another object is the provision of such a vise which is easy and inexpensive to manufacture.

A further object is to provide such a vise with a convenient and simple arrangement for filling or refilling the fluid chamber. I

Yet another object is the provision of a vise wherein the clamping pressure can be quickly and easily ascertained.

received in a complementary axial hole or bore in the slide. Both of the pistons are also coaxial with the hole and the projection so that the cylinder bears in direct axial force-transmitting relationship on the clamping body and centering of the cylinder on the axis of the threaded tightening sleeve is automatic on inserting the projection in the hole.

According to another feature of the present invention the projection is formed with an internally threaded bore while the hole in the slide is throughgoing so that removal of the displaceable vise jaw exposes the end of the projection and of this threaded bore. A

. screw and a washer normally block this bore, but their removal allows simple andrapid filling or refilling of the fluid chamber for original setting up of the vise or replacement of fluid lost during use.

In accordance with yet another feature of this invention the cylinder is provided on one side with a pressure meter connected via a passage to the interior of the pressure chamber. A port is formed on the slide for viewing of this meter so that the worker can ascertain exactly how much pressure is being exerted on the workpiece.

DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the drawing in which: i Y

FIG. 1 isa vertical axial section through a vise according to the present invention;

FIG. 2 is an axial section through a portion of the vise of FIG. 1 taken in a plane orthogonal to the section plane of FIG. 1; and

FIG. 3 is a fragmentary side view of the vise portion shown in FIG. 2.

SPECIFIC DESCRIPTION The machinist vise according to this invention has a frame or housing 1 screwed to a fixed mounting plate 1a, here mounted in a horizontal position as on a drill press or the like. A movable clamping assembly or slide 2 is displaceable parallel to the plate In in the directions indicated by in-line arrows A and B to clamp a workpiece W between a fixed jaw 3 held by bolts 33 on the frame or housing 1 and a movable jaw 4 held by bolts 35 on the end of the slide clamping assembly or 2.

The position of the clamping assembly or slide 2 is determined by a piston-and-cylinder arrangement having a cylinder chamber 5 formed in a'cylinder member 40 fastened to the clamping assembly or slide 2 by bolts 44..A piston 7 is slidable axiallyin the member 40 and surrounds a piston 6 while having an effective surface area equal to around twelve times that of the piston 6 to pressurize hydraulic fluid F (here oil) in the chamber 5. A gland 8 is provided to prevent leakage around and between the coaxial pistons 6 and 7. The piston 6 is received in the wide-diameter portion of a stepped bore 6a in the piston 7 so that movement of piston 7 in direction A also moves piston 6 in this direction.

The cylinder 40 has an end wall 41 formed with an extension 42 coaxial with the axis A of the vise. This projection 42 is received snugly in a correspondingly shaped bore 43 being open behind the jaw 4. In addition the projection 42 is formed with a coaxial threaded bore 45 that is normally plugged by a removable screw 46. The bore 45 is open into the chamber 5, or an extension thereof which can receive the piston 6 when it is displaced as far as possible in the direction of arrow A.

A sleeve 10 is threaded through an arm 11 formed on the frame 1 and bears via springs v12, axially abutting caps 13 and 7a, and springs 14 on the piston 7. These springs 12 and 14 are stacks of belleville washers. The slide 2 has an axial extension 15 formed with a bore 16 snugly receiving a cylindrical portion of the sleeve 10 between a shoulder and a snap ring 34, leaving a small amount of play. Thus it should be clear that a rotation of the sleeve 10 in one direction relative to the support 1 will move the jaw 4 in the direction of arrow A towards the jaw 3, and an opposite rotation will separate these jaws 3 and 4 by retraction of jaw 4 in direction B. As the sleeve 10 is advanced toward the jaw 3 it bears via the springs12, caps 13 and 7a, and springs 14 on the piston 7 which in turn bears on the slide 2 to move the jaw 4. The piston 6 is moved in direction A with the piston 7. The fluid F in chamber is kept under pressure by springs 13b surrounding screws 13a received in member 40. The springs 14 are maintained in a prestressed condition by a nut 711 on the piston 7.

A rod 9 passes axially through the cap 13 and extends into the interior of the hollow sleeve 10, with its lower end bearing on the piston 6 and its upper end bearing on an end of a rod 17 axially slidable in the sleeve 10. Another pin 18 engages the upper end 17a of the pin 17 and is axially couplable with another sleeve or nut 19 carried on the upper end of the sleeve 10. The sleeve and nut 19 are rotationally couplable through a torque coupling shown at 20. At the same time the nut 19 is axially fixed relative to the sleeve 20 by a snap ring 22 on one side and a flange 21 on the other side.

The nut 19 threadedly' engages a threaded region 23 of the pin 18 which is prevented from rotating relative to the sleeve 10 by means ofa transverse pin 25 passing through the lower end 24 of the pin 18 and engaging in axial grooves 26 formed in the interior of'the sleeve 10. These grooves 26 have an axial length at least equal to the axial travel of the piston 6.

The torque coupling 20 is formed by axially interengaging V-shaped teeth 29 formed on one end of the sleeve 19 and on the confronting surface of a ring or bushing 27 urged into contact with this sleeve 19 by a spring 28. The bushing 27 snugly receives the pin 25 and coupling the spindle 18 to the sleeve 10 for joint rotation thereof. Thus, unless there is undue resistance to rotation, the teeth 29 will couple the sleeves l9 and 10 together through the intermediary of the pin 25 passing through the ring 27. To rotate the sleeve 19 a crank 32 is-fitted into a hexagonal socket 31 in the upper end of this sleeve 19.

Axially dis placeable relative to the upper part 39 of the sleeve 10 is a ring 37 provided with a pin 38 engageable in axial bores 40a formed in this upper section 39. A key 43a engageable in an axial slot in the ring 37 totationally couples this ring 37 and the sleeve 19 while a spring-loaded pin 41a is engageable in a pair of axially spaced recesses to retain the ring in an up or down position as described below.

As shown in FIGS. 2 and 3 the cylinder member is formed with a lateral projection 47 which is in line with a round port 50 formed in the wall of the slide 2. A radial passage or conduit 48 leads from the base of a threaded cylindrical socket 52 formed in the projection 47 to the chamber 5. A pressure guage 49 is screwed into thissocket 52 through the port 50. A seal 51 is provided between the inner edge of the port 50 and the gauge 49 to prevent workpiece shavings and the like from entering the works of the slide 2.

The vise described above is assembled in the usual manner, except that the entire assembly of piston 7 and 6, cylinder 40, cap 7a, prestressing nut 7b, and springs 14 are fitted into. the slide 2 as a single unit and secured by bolts 44. Thereafter the cap 13 and various rods 9 and 17 are mounted along with the structure in the vise handle, and finally the snap ring 34 is mounted. The gauge 49 is screwed into place after the screws 44 are tightened. Only the jaw 4 is left off to permit access to the filling hole 45. Hydraulic fluid F is injected into the chamber 5 through this hold 45, the screw 46 with its washer-seal is driven home, and jaw 4 is secured with screws 35. The original filling of the chamber 5 is executed with the pistons 6 and 7 fully withdrawn in direction B. It has been found to be advantageous to fill the chamber 5 completely and close the bore before screwing the screws 13a completely home. This method insures that the fluid F in chamber 5 is always somewhat pressurized to prevent leakage.

The vise described above functions as follows:

A workpiece W is set between the open jaws 3 and 4 of the device and the crank 32 is rotated in the clockwise direction. Rothation of this crank 32 is transmitted by the teeth 29 to the ring 27 and therethrough to the pin 25 which rotates the sleeve 10 relative to its support arm 11, thereby advancing this sleeve 10 in the direction A. Since the sleeve 10 bears through springs 12 and 14 and members 13 and 7a on the piston 7, this piston will build uppressure in the cylinder chamber 5 to displace the jaw 4 in direction A also.

As soon as the jaws 3 and 4 close on the workpiece W the sleeve 10 will offer resistance to rotation over and above the normal frictional resistance of advance. At this time the springs 28 will compress to allow the teeth 29 to slip relative to each other, causing the nut 19 to rotate relative to the sleeve 10. This rotation will screw the pin 18 in the nut 19, forcing it downwardly. This motion is transmitted by rods 17 and 9 to the piston 6 to advance this smaller-diameter piston into the chamber 5. Since the effective surface area of piston 6 is only a fraction of that of the piston 7 and since the pitch of the threads on section 23 is much smaller than that of the threads between the sleeve 10 and the arm 11, the crank 32 is thereby effective with a greatly increased mechanical advantage to clamp the workpiece W between the jaws 3 and 4. Of course the teeth 29 only slip for a very brief time since after only one or two turns of the crank 32 the pin 18 pulls the ring 27 completely out of engagement with the teeth 29 on the sleeve 19,

The workpiece is released by counterclockwise rotation of the crank 32 which first pulls back the pin 18 in direction B and, when the teeth 29 reengage, rotates the sleeve 10. Thus the piston 6 will always be fully withdrawn when the fast-advance operation is commenced. The springs 12 and 14 insure that any minor leaks of fluid F are taken up without releasing the workpiece.

Should for some reason the workpiece get wedged between the jaws so tightly that on retraction of the jaw 4 the teeth 29 disengage, the ring 37 can be pushed down so that its pin 38 engages in one of the bores 40 to couple the sleeves l9 and rotationally, thereby making forcible withdrawal of the jaw 4 possible. This auxiliary rotational coupling is also useful on excessively resilient objects which must be tightly clamped.

The clamping pressure can be read directly off the liquidpressure gauge 49 to permit the operator of the vise to know just how tightly he is clamping the workpiece W. This gauge 49 permits him to apply the greatest possible amount of force to a workpiece without crushing it, since he need merely experiment with one workpiece to find its limits, note the pressure at which;

it deforms, and then stay below that pressure level with subsequent similar workpieces. Setup and use is extremely easy with such a vise.

I claim:

1. A clamping device comprising:

a support;

a stationary jaw carried on said support;

an elongated clamping slide axially displaceable along said support and having an axial hole;

a cylinder structurally independent of said slide and having a fluid chamber and an axial projection coaxial with said chamber and axially received in said hole;

an axially displaceable jaw carried on said slide and confronting said stationary jaw; v

a small piston coaxial with said hole, said projection and said fluid chamber and axially displaceable in said chamber; I

an actuator on said slide;

means between said actuator and said large piston for displacing said large piston axially toward said stationary jaw until said displaceable jaw encounters a predetermined axially directed resistance;

.means between said actuator and said small piston for displacing said small piston axially toward said stationary jaw after said displaceable jaw encounters said predetermined axially directed resistance; and

a sleeve threadedly received in said support and having one end carrying said actuator and another end engaging said large piston, the first-mentioned means including a slip clutch between said sleeve and said actuator for rotationally coupling said sleeve and said actuator until said predetermined resistance is encountered, the second-mentioned means including a spindle threadedly engaged in said actuator and rotationally coupled to said sleeve, said spindle being operatively engaged between said actuator and said small piston.

2. The device defined in claim 1 wherein said cylinder is formed with a threaded filling bore extending axially through said projection and opening into said chamber, said 'device -further comprising a screw threadedly received in and blocking said here, said displaceable jaw overlying said hole in said slide.

3. The device defined in claim 1, further comprising spring means for pressurizing fluid in said chamber.

4. The device defined in claim 3 wherein said spring means includes at least'one spring operatively engaged between said large piston and said cylinder and urging said large piston into said chamber.

5. The device defined in claim 1 wherein said cylinder is formed with a lateral projection, said slide being provided with a port in line with said lateral projection, said device further comprising a pressure gauge carried on said lateral projection an visible from outside said device through said port, said gauge being connected to said chamber to indicate pressure therein.

6. The device defined in claim 5 wherein said lateral projection is formed with a threaded socket receiving said gauge and with a passage communicating between the base of said hole and said chamber.

7. The device defined in claim 6 wherein said gauge extendsinto said port and is snugly received therein. 

1. A clamping device comprising: a support; a stationary jaw carried on said support; an elongated clamping slide axially displaceable along said support and having an axial hole; a cylinder structurally independent of said slide and having a fluid chamber and an axial projection coaxial with said chamber and axially received in said hole; an axially displaceable jaw carried on said slide and confronting said stationary jaw; a small piston coaxial with said hole, said projection and said fluid chamber and axially displaceable in said chamber; an actuator on said slide; means between said actuator and said large piston for displacing said large piston axially toward said stationary jaw until said displaceable jaw encounters a predetermined axially directed resistance; means between said actuator and said small piston for displacing said small piston axially toward said stationary jaw after said displaceable jaw encounters said predetermined axially directed resistance; and a sleeve threadedly received in said support and having one end carrying said actuator and another end engaging said large piston, the first-mentioned means including a slip clutch between said sleeve and said actuator for rotationally coupling said sleeve and said actuator until said predetermined resistance is encountered, the second-mentioned means including a spindle threadedly engaged in said actuator and rotationally coupled to said sleeve, said spindle being operatively engaged between said actuator and said small piston.
 2. The device defined in claim 1 wherein said cylinder is formed with a threaded filling bore extending axially through said projection and opening into said chamber, said device further comprising a screw threadedly received in and blocking said bore, said displaceable jaw overlying said hole in said slide.
 3. The device defined in claim 1, further comprising spring means for pressurizing fluid in said chamber.
 4. The device defined in claim 3 wherein said spring means includes at least one spring operatively engaged between said large piston and said cylinder and urging said large piston into said chamber.
 5. The device defined in claim 1 wherein said cylinder is formed with a lateral projection, said slide being provided with a port in line with said lateral projection, said device further comprising a pressure gauge carried on said lateral projection an visible from outside said device through said port, said gauge being connected to said chamber to indicate pressure therein.
 6. The device defined in claim 5 wherein said lateral projection is formed with a threaded socket receiving said gauge and with a passage communicating between the base of said hole and said chamber.
 7. The device defined in claim 6 wherein said gauge extends into said port and is snugly received therein. 